This project is designed to study the role of occult myocardial failure in the development of human shock. Another aspect of tis project is the evaluation of myocardial depression in producing abnormal recovery from major surgical procedures and methods of protecting the patient against untoward effects of surgery. As a specific aspect of this we are studying optimal methods of myocardial preservation during cardiopulmonary bypass. BIBLIOGRAPHIC REFERENCES: Raza, S.T., Vidne, B.A., Farrell, E.J., Lajos, T.Z., Lee, A.B., Schimert, G., and Siegel, J.H. "Early and Longterm Effects of Direct Myocardial Revascularization: A Prospective Study Using Multivariable Physiologic Analysis: Cardiac Function After Direct Myocardial Revascualarization". Circulation, 1976. Farrell, E.J., Siegel, J.H. "Estimation of Blood Gas Contents from Expired Air Under Normal and Pathologic Conditions" Respiration Physiology, 1976, Vol. 26, pp. 303-325.